Verses with the word avenge in the New Testament (6 verses):

Luke 18:3
And there was a widow in that city; and she came unto him, saying, Avenge me of mine adversary.

Luke 18:5
Yet because this widow troubleth me, I will avenge her, lest by her continual coming she weary me.

Luke 18:7
And shall not God avenge his own elect, which cry day and night unto him, though he bear long with them?

Luke 18:8
I tell you that he will avenge them speedily. Nevertheless when the Son of man cometh, shall he find faith on the earth?

Romans 12:19
Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.

Revelation 6:10
And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?